Question

What is Nernst equation and give its significance ?

Answer 1

Nernst gave a relationship between electrode potential and concentration of electrolyte solution known as Nernst equation. For a general electrode reaction,
Mⁿ⁺(aq) + ne^- $\to$ M(s)
the Nernst equation is

$E\left(M^{n+}\right|M)=E°(M^{n+}\left|M\right)-\frac{RT}{nF}\ln \frac{\left[M\right(s\left)\right]}{\left[M^{n+}\right(aq\left)\right]}$

Where E(Mⁿ⁺|M) = electrode potential
E^o​(Mⁿ⁺|M) = Standard electrode potential
R = Gas constant, T = Temperature, F = Faraday constant
n = Number of electrons gained during electrode reaction
[Mⁿ⁺(aq)] = Molar concentration of ions, [M(s)] = concentration of metal

Significance of Nernst equation:
1) It can be used for calculation of cell potential
2) ​It can be used for calculation of concentration of a solution of Half cell.
3) Equilibrium constant can be calculated from this equation.